On vintage Honda forums I see a lot of bashing of these bikes' charging systems. That's messed up. The people asking the questions are badly served by these forums' "experts" who tell them they can't run even a quartz headlight.
After a lot of thought, and some invigorating give and take on the forums, I think the issue may boil down to two things. First, folks demand more of their bikes electrically than ever before. Living in the west I am not as close as I might otherwise be to the heated clothing ethic that seems to permeate much of the country. Can't argue with the fact that a bike whose charging system is rated at only 200 watts isn't going to do well with 180 watts of electric jackets and pants and whatnot plugged in. That's an easy one.
The second issue is more complex, and to me the more important one. In this day when all but ultrasport bikes have low rev limits and broad powerbands, folks I believe have forgot how 70s motorcycles, and Hondas in particular, were designed. You just don't properly ride SOHC Honda fours at 4,000 rpm and less. Why would you? They don't make any power down there, they don't feel right sound right go right. I just don't quite get it.
Another thing I don't get is this fixation so many on forums have of vintage Honda fours not charging at idle. So what? They never did, even new, and what is the point? The only reason cars do is their alternators are "pullied up", that is, their rubber belt drive ratio is multiplied upward for greater ouput. 70s Hondas don't have this advantage, their charging systems being made a part of the engine. Their electromagnet charging systems therefore don't exceed an equilibrium point until about 1700 rpm. Again, so? I am at a loss as to why forum folks insist their systems should charge at idle. How often do you operate a bike at idle? And even if you do sit at tollway booths or in traffic some, that's not going to kill your battery unless you have a fault im either your battery or your charging system. I just can't understand why folks don't realize no one even gave this a thought until the emergence of user forums.
The fact is, maintained correctly and ridden properly, and excepting loads of heated clothing, there is plenty of electrical margin in these old bikes. Do these naysayers think that CB550 and CB750 riders struggled with dead batteries back in the day? Really? My 200-watt1 alternator equipped CB500 four had an 80-watt quartz headlight, current-doubling high output ignition coils, ignition points set to maximum dwell, an alarm system, and even more powerful horns. And never had a problem. Of course I had the regulator turned up, a viable and legitimate adjustment option available to the riders of many of these old fours, despite some on forums who recommend against iy. I also still own a CBX having a slightly stronger 300-watt system. Once the CBX's drive clutch is attended to and you resign yourself to replacing brushes every 15,000 miles, it is likewise faultless and much more than adequate, at least to this So Cal resident. And this is a touring bike.
Don't dismiss the standard vintage Japanese bike's charging system, and certainly don't do so out of hand. While it can't compare with that found on a modern luxo-tourer, it is pretty powerful for all that and has served owners of these machines more than adequately by supporting more than original equipment loads for almost three generations.
Postscript October 2014: I see the forum experts are still at it, telling folks they can't run both Dyna coils and a quartz headlight on their CB550s. Sigh.
1 This is official Honda specification, CB500/550 manual, published 1974, page 136.
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